Several differing mechanisms exist which claim to permit the storage of two or more constituent compounds and adjustment of the relative concentration of the product dispensed. Each of these mechanisms, however, possess one or more design flaws which may impede the product's functionality. These flaws tend to fall into four categories: energy transmission, time to outlet, relative viscosities, and excessive reservoir/inadequate mixing.
Energy Transmission: All multi-chamber "squeeze type" bottles suffer, to one degree or another, from problems involving energy transmission. In the squeeze type bottle, it is necessary for the user to apply pressure to each compartment in order to displace that compartment's contents. To ensure consistency of the amalgamated product, the relative pressure that the user applies to each of the compartments must remain constant throughout compression and from use to use. If, for example, the user changes his grip or the contents of one compartment have been depleted, then the relative pressure applied and, accordingly, the relative quantity of each liquid delivered will vary. This problem is clearly evident in the mechanisms described in the Iggulden et al, Swahl et al, and Voulgaris patents (U.S. Pat. Nos. 4,893,729; 4,838,457; and 3,918,612, respectively). It is, however, minimized in the mechanisms described in the Becker et al, Richardson et al, Darbon et al, and Zulauf patents (U.S. Pat. Nos. 4,993,594; 3,850,346; 3,814,287; and 4,585,149, respectively).
Time to Outlet: In all multi-liquid containers, it is essential that each of the constituent liquids reach the container outlet simultaneously. If one constituent liquid reaches the outlet prior to the other constituent liquid(s), the initial output will consist of the "fast moving" constituent liquid only. The greater the viscosity of the liquids or the greater the difference between the viscosity of the liquids, the greater the problem. This problem is especially evident in "pour type" squeeze bottles such as those described in the Iggulden et al, Swahl et al, and Voulgaris patents (U.S. Pat. Nos. 4,893,729; 4,838,457; and 3,918,612, respectively). The problem, however, can be minimized in those squeeze bottles which draw liquid from the bottom of the container such as the mechanism embodied in the Becker et al patent (U.S. Pat. No. 4,993,594).
Relative Viscosities: As discussed previously, squeeze bottles suffer from a variety of problems including energy transmission and "time to outlet". These problems may be exacerbated if the viscosities of the constituent liquids differ markedly. The relative viscosities of the constituent liquids, however, have an even more profound impact on the functionality of "pump type" bottles. If the pump type bottle utilizes a single pump to draw more than one constituent liquid, it will preferentially draw the liquid with the lower viscosity (i.e., take the course of least resistance). Thus, for example, if one chamber contains ketchup and the other contains water, the pump will tend to draw water only. Further, once any constituent liquid has been depleted completely, the pump will draw only air (the least viscous compound) and cease to work. This problem exists, for example, in the mechanisms described in the Vierkotter patent (U.S. Pat. No. 4,355,739) and in the Metzler patent (U.S. Pat. No. 3,786,963). The problem does not exist with multiple pump designs such as those described in the Skorka et al and Castner et al patents (U.S. Pat. Nos. 4,826,048 and 3,760,986, respectively).
Excessive Reservoir/Inadequate Mixing: Delivery of the constituent liquids in blended form creates a dilemma. On the one hand, it is desirable to mix the constituent liquids thoroughly prior to delivery. On the other hand, it is advantageous for the user to receive the desired concentration immediately rather than first having to clear the remnants of the previous mix. In order to mix the constituent liquids thoroughly, they must be combined and mixed within the dispenser. This, however, involves the creation of a reservoir containing the constituent liquids at a specific ratio. Thus, upon each use, the user will initially receive a mix of the constituent liquids at the concentration of the previous use. Only after the contents of the reservoir have been replaced completely will the user receive the desired mix. Several patents reveal dispensers with excessively large reservoirs. Further, in most of these mechanisms, no mechanical means is utilized to mix the constituent liquids (other than uniting them in a con, non chamber). Richardson et al (U.S. Pat. No. 3,850,346) discloses use of a sequential baffling system to provide thorough mixing; Skorka et al (U.S. Pat. No. 4,826,048) discloses use of helical or spiral groove-like swirl channels to intensely mix components; Darbon et al (U.S. Pat. No. 3,814,287) discloses an acknowledgment of a need for a device to facilitate uniform blending. Therefore, not only is there often a large reservoir, but such reservoir generally adds little to the functionality of the product as in Iggulden et al (U.S. Pat. No. 4,893,729), Vierkotter (U.S. Pat. No. 4,355,739), Zulauf (U.S. Pat. No. 4,585,149), and Ducros et al (U.S. Pat. No. 4,460,109).